A second application of hierarchical VPLS is using MTUs that are MPLS-enabled which must have spoke-SDPs to the closest PE node. To protect against failure of the PE node, an MTU can be dual-homed.
The following are several mechanisms that can be used to resolve a loop in an access network where 7210 SAS devices are used:
STP-based access, with or without mVPLS
Ethernet APS using G.8032